Logger

Awkernel uses log crate for logging. So, you can use the log macros like defined in this crate as follows. The logger uses the console module internally.

#![allow(unused)]
fn main() {
log::error!("This is an error message.");
log::warn!("This is a warning message.");
log::info!("Hello, world!");
log::debug!("This is a debug message.");
log::trace!("This is a trace message.");
}

log::debug! is useful when implementing and debugging the kernel because it displays a message with the file name and line number where the macro is called.

You can use log::set_max_level function to set the maximum log level as follows.

#![allow(unused)]
fn main() {
log::set_max_level(log::LevelFilter::Trace);
}

Buffered Logger

After booting Awkernel, the logger implementation defined in awkernel_lib/src/logger.rs is switched to a buffered logger defined in applications/awkernel_services/src/buffered_logger.rs. The buffered logger buffers log messages and writes them to the UART in a batch. Note that the buffered logger will discard messages if the buffer is full to avoid memory exhaustion. The buffered logger is executed as an async/await task and spawned in applications/awkernel_services/src/main.rs.